The invention discloses a mesoporous perovskite solar cell and a preparation method thereof. The mesoporous perovskite solar cell comprises a transparent conductive base, a compact layer, a skeleton layer, a perovskite layer, a hole transmission layer and a counter electrode, wherein the compact layer, the skeleton layer, the perovskite layer, the hole transmission layer and the counter electrode are sequentially stacked on the transparent conductive base; and the skeleton layer is a barium stannate film with a perovskite structure and the like, and has p-type conductivity or n-type conductivity or comprises an insulator. With a novel perovskite oxide as the skeleton layer, the mesoporous perovskite solar cell has relatively high charge collection efficiency, and is relatively good in contact with a perovskite layer interface. Compared with a traditional titanium dioxide compact layer, the photoelectric properties such as short-circuit current and filling factors can be effectively improved; leakage current caused by contact of the hollow transmission layer and an electron transmission layer is reduced; reverse recombination of photoelectrons is prevented; and the photoelectric conversion efficiency is improved.